Stuck at 30psi

[kmorgan23]

Hi everyone, new to the forum, been fixing up my old 87 b2 for about a year. Have replaced or fixed literally most everything, and completed an engine rebuild in March. Before the rebuild and after, I am STILL stuck at 30psi on the fuel rail, and am officially at a loss at where the issue may be.

I most recently replaced the cheap in tank pump with a Delphi in tank pump to match the high pressure pump. Filters new, injectors new and clean, replaced the lines, new cats and muffler, you name it.. it's probably been replaced.

Any ideas? The result of 30psi is real sluggish driving and acceleration. Have been able to make it my daily, but can only get to 55mph on a straight away, hills... I'm a grandma in the slow lane.

 

[Uncle Gump]

Does your truck only have the one in tank pump? My 86 has a low pressure in tank and a high pressure frame mounted pump.

 

[fastpakr]

Isn't 30 or so the correct pressure when the engine is running with vacuum applied to the regulator?

 

[kmorgan23]

Does your truck only have the one in tank pump? My 86 has a low pressure in tank and a high pressure frame mounted pump.

There is an in tank pump and high pressure pump on the frame. Both have been replaced.

 

[kmorgan23]

Isn't 30 or so the correct pressure when the engine is running with vacuum applied to the regulator?

Normal should be 40psi, and currently under load there's no increase. Just stays at 30psi, whether at idle or acceleration.

 

[fastpakr]

Thanks - it's been a while since I've had the return less 99 for the last few years.

Have you given the regulator a close look?

 

[kmorgan23]

Thanks - it's been a while since I've had the return less 99 for the last few years.

Have you given the regulator a close look?

No problem! Regulator is new as well. Made checks on it to make sure it was working properly. No leaks, no issues.

 

[fastpakr]

Does it maintain pressure after shutdown?

 

[kmorgan23]

Does it maintain pressure after shutdown?

It does not, but didn't specifically check.. I just noticed yesterday, when I first attached the fuel pressure gauge (has a bleeder hose) to purge pressure so I could replace the pump, there was no pressure to purge.

 

[Uncle Gump]

Even though you checked it... the fuel pressure regulator doesn't sound like it's working properly. Or... your high pressure pump won't make more then 30 psi.

 

[kmorgan23]

Even though you checked it... the fuel pressure regulator doesn't sound like it's working properly. Or... your high pressure pump won't make more then 30 psi.

I'll dig into it today and report back. Thanks!

 

[kmorgan23]

Even though you checked it... the fuel pressure regulator doesn't sound like it's working properly. Or... your high pressure pump won't make more then 30 psi.

Well. It's not the regulator, I replaced with a gp Sorenson brand and made no difference.. It's not either of the two pumps. The in tank was replaced two days ago, interchanged high pressure with an older, working pump, with no change. Tried blowing into the return line, and got full resistance, so I removed the fuel reservoir canister permanently and directly connected the fuel lines to the tank. Still no improvement. I removed the refurb fuel injectors, replaced with the fully cleaned original injectors (with new o rings and points) and made sure of proper seating. No improvement. I'm completely, completely in the dark as to why I have such a loss in power (and high fuel consumption). I'm now desperate for help as I am moving and will have a much longer work commute.

 

[Uncle Gump]

Does the fuel pressure change when you disconnect the fpr vacuum hose?

Where is base timing?

Did you reconnect spout connector?

Have you checked for restricted exhaust?

 

[kmorgan23]

1. Yes, but only 1-2psi

2. 10btdc is base, but I'm in Colorado so I have it set at 12 degrees

3. Yes

4. Exhaust is all new.. manifolds, cats, muffler

 

[Uncle Gump]

Have you tried cursing at it?